1. Field of the Invention
The present invention relates to a jet ink composition. Particularly, it relates to a jet printing liquid ink composition to be used for a printer in an ink jet system.
2. Description of the Prior Art
Printing by an ink jet printer involves feeding an ink to a fine nozzle (inner diameter of 10.mu.(m - 120.mu.m) made of metal or glass, injecting uniform ink particles from the top of the nozzle and electrostatically deflecting the ink particles by a deflecting electrode disposed in front of the nozzle so as to print a symbol corresponding to a predetermined dot-matrix. The key problems areas of technology for the ink jet printer have concerned the development of methods for dividing the ink in the nozzle into fine ink particles and methods for controlling the injecting direction by a deflection plate or by movement of the nozzle. It is clear that the characteristics of the ink are a critical consideration in these technological areas. Accordingly, the characteristics required for the jet ink composition include stability while being injected as particles by pressure and electrical field, high deflection sensitivity and ease in being discharged from the nozzle under the mutual interaction of ink and nozzle. Moreover, the ink must possess the basic characteristics needed by inks in any printing system, e.g., sufficient fluidity, to prevent closing of the nozzle by drying of the ink in the nozzle.
Conventional jet printing inks are classified as aqueous or nonaqueous. The nonaqueous inks have the disadvantages of low stability of injected ink particles caused by low surface tension. They easily form a mist in the flying step, i.e., under the influence of the electric field. Additionally they have high electrical resistance, i.e., low deflection sensitivity, and low stability of ink particles in a high electric field. Consequently, using them it has been difficult to print clear symbols by conventional apparatus. It would be most desirable to have a nonaqueous ink free from the aforementioned disadvantages.